1. Field of the Invention
This invention relates to an improved reversing valve construction and to an improved piston head assembly for such a reversing valve construction or the like as well as to improved methods of making such a reversing valve construction and such a piston head assembly.
2. Prior Art Statement
It is known to provide a reversing valve construction having a housing means provided with a movable valve member therein that is interconnected to a piston unit disposed in the housing means and having opposed piston heads each of which has a flexible seal member secured between a front disc member and a backing plate of the respective piston head so that an integral peripheral skirt of that seal member is urged into sliding and sealing engagement with an internal peripheral surface of the housing means by a biasing means of a respective piston head.
For example see the following patent:
(1) U.S. Pat. No. 3,056,574--Greenawalt.
It appears that the flexible skirt of the resilient seal member for each piston head of the reversing valve construction of item (1) above is urged radially outwardly by a metallic washer-like spring member.
It is also known to urge an annular flexible boot of a piston head assembly radially outwardly by a flexible O-ring member carried by the piston head assembly.
For example, see the following U.S. Patent:
(2) U.S. Pat. No. 3,448,959--McHale et al.
It appears that a flexible annular tubular boot member is urged radially outwardly by a resilient O-ring member at each piston head assembly of the reversing valve construction of item (2) above.
However, the use of a resilient O-ring member for urging a cup-shaped flexible sealing member radially outwardly into sealing and sliding engagement with the internal peripheral surface of a housing means is well known. For example, see the following U.S. patent:
(3) U.S. Pat. No. 3,603,215--Leschisin
It appears that a flexible cup-shaped seal member of a movable piston head is urged radially outwardly by a resilient O-ring member compressed between the outer peripheral part of the cup-shaped resilient seal member and a rigid backing part of the piston head which clamps the cup-shaped sealing member against another rigid part of the piston head assembly.
It is also known to provide a reversing valve construction having a housing means provided with a movable valve member therein that is interconnected to a piston unit disposed in the housing means having opposed piston heads each of which has a flexible seal member provided with a peripheral skirt disposed in sliding and sealing engagement with the internal peripheral surface of the housing means so as to define a main chamber between the piston heads and a pair of outboard control chambers respectively disposed between the piston heads and opposed ends of the housing means, each piston head having means for closing a valve seat carried by the respective end of the housing means.
For example, see the following U.S. patent:
(4) U.S. Pat. No. 3,032,312--Greenawalt
It appears that each piston head assembly carries a frusto-conical valve member which is inserted into a valve seat carried by the end of the housing means of the reversing valve construction of item (3) above to close the same.
(5) German Pat. No. 1,110,970--Renault.
It appears that certain of the piston head assemblies of item (5) above each has a peripheral skirt on the flexible sealing member of the reversing valve construction that slides in sealing contact with the annular peripheral surface of the housing means containing the same, each sealing member also having a flexible portion for sealing against a respective opposed end wall of the housing means to seal a valve seat structure thereof.